linux-kernel - Re: [PATCH V2 24/30] serial: qcom: Migrate to dev_pm_opp_set

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Date:   Fri, 1 Jul 2022 15:31:00 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Jiri Slaby <jirislaby@...nel.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>, Nishanth Menon <nm@...com>,
        linux-arm-msm@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 24/30] serial: qcom: Migrate to dev_pm_opp_set_config()

On 01-07-22, 11:39, Greg Kroah-Hartman wrote:
> It's now more complex for simple drivers like this, right?

They need to add a structure, yes.

> Why not
> provide translations of the devm_pm_opp_set_clkname() to use internally
> devm_pm_opp_set_config() if you want to do complex things,

That can be done, yes.

> allowing you
> to continue to do simple things without the overhead of a driver having
> to create a structure on the stack

I didn't think of it as complexity, and I still feel it is okay-ish.

> and remember how the "const char *[]"
> syntax looks like (seriously, that's crazy).

The syntax can be fixed, if we want, by avoiding the cast with
something like this:

diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
index a018b45c5a9a..1a5480214a43 100644
--- a/drivers/mmc/host/sdhci-msm.c
+++ b/drivers/mmc/host/sdhci-msm.c
@@ -2559,8 +2559,9 @@ static int sdhci_msm_probe(struct platform_device *pdev)
        const struct sdhci_msm_offset *msm_offset;
        const struct sdhci_msm_variant_info *var_info;
        struct device_node *node = pdev->dev.of_node;
+       const char *clks[] = { "core" };
        struct dev_pm_opp_config opp_config = {
-               .clk_names = (const char *[]){ "core" },
+               .clk_names = clks,
                .clk_count = 1,
        };

> Make it simple for simple things, and provide the ability to do complex
> things only if that is required.

I still feel it isn't too bad for simple cases right now too, it is
just a structure to fill out but I don't have hard feelings for
keeping the old API around. I just feel it isn't too helpful to keep
the old interfaces around, it will just confuse people at the best.

Anyway, I will keep them around.

-- 
viresh